thumb|Scallop shell offering hospitality to pilgrims on the [[Camino de Santiago|Way of St James]]
Hospitium (; , xenia, προξενία) is the ancient Greco-Roman concept of hospitality as a divine right of the guest and a divine duty of the host, or hospes. Similar or broadly equivalent customs were and are also known in other cultures, though not always by that name. Among the Greeks and Romans, hospitium was of a twofold character: private and public.
Private
In Homeric times, all strangers, without exception, were regarded as being under the protection of Zeus Xenios, the god of strangers and suppliants, and had the right to hospitality. (It is doubtful whether, as is commonly assumed, they were considered as ipso facto enemies; they were rather guests.) Immediately on his arrival, the stranger was clothed and entertained, and no inquiry was made as to his name or antecedents until the duties of hospitality had been fulfilled. When the guest parted from his host he was often presented with gifts (ξένια), and sometimes a die (ἀστράγαλος) was broken between them. Each then took a part, a family connection was established, and the broken die served as a symbol of recognition; thus the members of each family found in the other hosts and protectors in case of need.